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Full text of "The Cambridge Natural History"

STOMACH AND BRAIH

ally appear, the first three are considered to correspond to pre
molars. But successional teeth are rare in the genus ; that is t<
say as far as concerns the molars, for the tusks have their mill
forerunners. As to the molars it is apparently only 1$. planifron^
which certainly shows a milk dentition. In Mastodon and oldei
types a milk dentition Is commoner.
The "viscera of the Elephant have been examined by many
zoologists. The latest paper, dealing chiefly with the African
species, but containing facts about its Indian congener also, is quoted
below.1 The Elephant is remarkable in possessing, in addition
to the three usual pairs of salivary glands present in mammals, a
fourth, situated in the molar region, and opening on to the cheek
by many pores. This gland is especially well developed in Hodents.
There is a gland which may be mentioned in this connexion, though
it opens externally between the eye and ear, known as the temporal
gland ; its use does not seem clear. The thoracic cavity of the
Elephant, as may be inferred from the large number of ribs, is
very large as compared with the abdominal.
The stomach is simple in form, and the epithelium of the
oesophagus does not extend into it as is the case with the Horse
and Rhinoceros. A gland or a collection of smaller glands occurs
in the stomach, and recalls the " cardiac gland " of the "Wombat
and the Beaver, also that of the Giraffe. The large intestine is
long, rather more than half the length of the small intestine.
The caecum is well developed in these animals. The liver has a
very simple form, being but slightly lobulated. It is actually
only bilobed, but it is important to notice that this division does
not correspond to the two halves of the liver. As shown by
the attachment of the suspensory ligament, one half consists of
the left lateral lobe alone, the other half embracing the remaining
primary lobes. The simplicity of the liver looks like an archaic
character. No Elephant has a gall-bladder. The lungs again are
simple in form through their slight lobulation. Each half in
fact is without subdivisions, and is of a triangular form. In
this the Elephants resemble the "Whales, as in the simple liver.
In both cases probably the likeness is due to the permanence of
primitive features of organisation. The brain 2 of the Elephant
1 Forbes, JProc.   Zool, Sac. 1879, p. 420.
a See Krueg, Zettscfcr. ixriss. Zool. xxxlii. 1381, pk 652, and Beddard, Proc. Zool.
8&cf 180af p. 311.